Difference Between Eddy Current and Induced Current

Eddy current and induced current are two valuable concepts in electromagnetic field theory. These two concepts have a wide range of applications in various fields. This article is about the basics of eddy current and induced current and the differences between the two concepts..

What is Induced Current?

Understanding of electromagnetic induction is essential, to understand induced current. Electromagnetic induction is the effect of current flowing through a conductor, which is moving through a magnetic field. The Faraday’s law is the most influential law regarding this effect. He stated that electromotive force produced around a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. If the closed path is a loop on a plane, the rate of magnetic flux change over the area of the loop is proportional to the electromotive force generated in the loop. However, this loop is not a conservative field now. Therefore, common electrical laws such as Kirchhoff’s law are not applicable in this system. It must be noted that a steady magnetic field, even if it were strong across the surface, would not create an electromotive force. The magnetic field must vary in order to create the electromotive force. This theory is the main concept behind electricity generation. Almost all of the electricity, except the solar cells, is generated using this mechanism. The electric field created by the electromagnetic induction is a non-conservative field. Therefore, conservative field laws such as Kirchhoff’s law are not valid in induced fields. For a non-conservative field, a single point can have two potential values.

What is Eddy Current?

An eddy current is produced when a conductor is exposed to a changing magnetic field. Eddy currents are also known as Foucault currents. These currents are usually generated in small closed loops inside the conductor. An eddy means a turbulence loop. The strength of the eddy current depends on the strength and rate of change of the magnetic field and the conductivity of the material. Eddy current loss is the main method of energy loss in transformers. If not for the eddy current loss, transformers would have efficiency of nearly 100%. The eddy current loss in transformers is minimized by using extremely thin conductor plates and having air gaps on the path of eddy currents. Eddy currents create a magnetic field opposing the change in the magnetic field. The phenomenon of eddy currents is used in applications such as magnetic levitation, identification of metals, position sensing, electromagnetic braking and structural testing. The eddy currents of a conductor are also dependent of the skin effect of the metal.

What is the difference between eddy current and induced current?

• Eddy currents are generated within the material, and induced currents are created within a closed circuit.

• Eddy currents are independent of the area of the conductor, but induced currents are dependent on the area covered by the circuit.

• Induced currents can be considered as the net amount of eddy currents generated in the material.